A major user group consisting of 8 faculty of the Departments of Pharmacodynamics and Pharmacology and Experimental Therapeutics of the University of Florida's College of Pharmacy and Medicine request a shared Quantitative Densitometry Instrument. This instrument would be used to conduct studies aimed at extending existing PHS grants in the following areas: (1) distribution and metabolism of novel brain-enhanced drug delivery systems (Simpkins and Bodor); (2) quantitative receptor autoradiography (Peris, Baker, Childers, Crews and Dawson); (3) in situ hybridization (Meyer); (4) intracellular ion metabolism (Dawson and Meldrum); and (5) detection of intracellular concentrations of ion and voltage-sensitive dyes (Dawson, Meldrum, Childers and Crews). The use of this instrument would focus mainly, but not exclusively, on quantitative densitometry of brain tissue. The requested instrument would be located in the laboratory of Dr. Joanna Peris, who among the major user group has extensive experience in quantitative densitometry methods. The use of this shared instrument would be guided by an Internal Advisory Committee consisting of James W. Simpkins, the P.I., Joanna Peris, who would oversee the day-to-day operation of the instrument and Edwin Meyer, a representative of the Department of Pharmacology and Experimental Therapeutics. The College of Pharmacy would support the requested instrument by providing 50% of the salary of a full-time technician for 3 years (major users would support the remainder of his/her salary), providing 1/2 of service contract cost for 1 year beyond the expiration of the warranty (major users would fund the remainder of the service contract costs) and by providing space to house the instrument and the technician.